Kombinere tung-ion-eksperimenter og kjernefysisk teori

Sammenslåing av nøytronstjerner og nye partikkelspor

Kunstnerens gjengivelse som viser simuleringen av to sammenslående nøytronstjerner (til venstre) og de nye partikkelsporene som kan sees i en tung-ion-kollisjon (til høyre) som skaper materie under lignende forhold i laboratoriet. Kreditt: Tim Dietrich, Arnaud Le Fevre, Kees Huyser; bakgrunn: ESA/Hubble, Sloan Digital Sky Survey

Kombinerer eksperimenter med tunge ioner, astrofysiske observasjoner og kjernefysisk teori.

Når en massiv stjerne eksploderer i en supernovahvis den ikke er fullstendig ødelagt, vil den etterlate seg enten en svart hull eller a[{” attribute=””>neutron star. These enigmatic cosmic objects are especially mysterious because of the crushing internal pressures resulting from neutron stars’ incredible density and the perplexing properties of the nuclear matter they are made of.

Now, an international team of researchers has for the first time combined data from heavy-ion experiments, gravitational wave measurements, and other astronomical observations using advanced theoretical modeling to more precisely constrain the properties of nuclear matter as it can be found in the interior of neutron stars. The results were published on June 8, 2022, in the journal Nature.

Neutron stars are formed when a giant star runs out of fuel and collapses. They are among the densest objects in the cosmos, with a single cube sized piece weighing 1 billion tons (1 trillion kg.)

Throughout the Universe, neutron stars are born in supernova explosions that mark the end of the life of massive stars. Sometimes neutron stars are bound in binary systems and will eventually collide with each other. These high-energy, astrophysical phenomena feature such extreme conditions that they produce most of the heavy elements, such as silver and gold. Consequently, neutron stars and their collisions are unique laboratories to study the properties of matter at densities far beyond the densities inside atomic nuclei. Heavy-ion collision experiments conducted with particle accelerators are a complementary way to produce and probe matter at high densities and under extreme conditions.

New insights into the fundamental interactions at play in nuclear matter

“Combining knowledge from nuclear theory, nuclear experiment, and astrophysical observations is essential to shedding light on the properties of neutron-rich matter over the entire density range probed in neutron stars,” said Sabrina Huth, Institute for Nuclear Physics at Technical University Darmstadt, who is one of the lead authors of the publication. Peter T. H. Pang, another lead author from the Institute for Gravitational and Subatomic Physics (GRASP), Utrecht University, added, “We find that constraints from collisions of gold ions with particle accelerators show a remarkable consistency with astrophysical observations even though they are obtained with completely different methods.”

Neutron Star Artist’s Depiction

Artist’s depiction of a neutron star. Credit: ESO / L. Calçada

Recent progress in multi-messenger astronomy allowed the international research team, involving researchers from Germany, the Netherlands, the US, and Sweden to gain new insights to the fundamental interactions at play in nuclear matter. In an interdisciplinary effort, the researchers included information obtained in heavy-ion collisions into a framework combining astronomical observations of electromagnetic signals, measurements of

Reference: “Constraining neutron-star matter with microscopic and macroscopic collisions” by Sabrina Huth, Peter T. H. Pang, Ingo Tews, Tim Dietrich, Arnaud Le Fèvre, Achim Schwenk, Wolfgang Trautmann, Kshitij Agarwal, Mattia Bulla, Michael W. Coughlin and Chris Van Den Broeck, 8 June 2022, Nature.
DOI: 10.1038/s41586-022-04750-w